Semiconductor device and method of manufacturing the same

ABSTRACT

The present invention provides a semiconductor device realizing reduced occurrence of a defect such as a crack at the time of adhering elements to each other. The semiconductor device includes a first element and a second element adhered to each other. At least one of the first and second elements has a pressure relaxation layer on the side facing the other of the first and second elements, and the pressure relaxation layer includes a semiconductor part having a projection/recess part including a projection projected toward the other element, and a resin part filled in a recess in the projection/recess part.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a Reissue Application of patent application Ser. No. 12/929,515,filed Jan. 31, 2011, now U.S. Pat. No. 8,450,752, issued May 28, 2013,which is a Divisional Application of patent application Ser. No.12/081,354, filed Apr. 15, 2008, now U.S. Pat. No. 7,880,178, issuedFeb. 1, 2011 which claims priority from Japanese Patent Application JP2007-110512 filed in the Japanese Patent Office on Apr. 19, 2007, theentire contents of which being incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having aplurality of elements stacked and a method of manufacturing the same.

2. Description of the Related Art

Hitherto, in a semiconductor device for a use of an optical fiber, anoptical disk, and the like, as part of an object of making the lightoutput level of a semiconductor light emitting element assembled in thedevice constant, emission light of the light emitting element isdetected by a light detecting mechanism. The light detecting mechanismmay be constructed by, for example, a reflector that branches part ofemission light and a light detecting element that detects the branchedemission light. In the configuration, however, the number of partsincreases and, moreover, a disadvantage occurs such that the reflectorand the light detecting element have to be disposed with high precisionwith respect to the light emitting element. As one of measures solvingsuch a disadvantage, the light emitting element and the light detectingelement are integrally formed.

However, when the light emitting element and the light detecting elementare formed integrally, there is the possibility that the light detectingelement detects not only stimulated emission light to be inherentlydetected but also spontaneous emission light. In such a case, the lightoutput level of the light emitting element measured on the basis oflight detected by the light detecting element includes an error only bythe amount of spontaneous emission light. Therefore, the method is alsonot suitable for uses necessitating high-precision control on the lightoutput level.

Japanese Patent No. 2,877,785 discloses a technique of providing acontrol layer in a light detecting element and interrupting part ofspontaneous emission light entering from a light emitting element beforethe light detecting element detects it.

The control layer is formed by oxidizing a part of the semiconductormaterial of the light detecting element. The reflectance of the oxidizedsemiconductor material is not so high, and the semiconductor materialtransmits some spontaneous emission light. It is therefore difficult tosufficiently lower the spontaneous emission light detection level of thelight detecting element. There is consequently a disadvantage such thatlight detection precision is not sufficiently improved.

SUMMARY OF THE INVENTION

To solve the disadvantage, there is a method of providing a controllayer having a light transmission part in an area corresponding to alight emission area of a light emitting element between the lightemitting element and a light detecting element and metal part havinghigh reflectance around the light transmission part, and efficientlyreflecting spontaneous emission light by the metal part having highreflectance.

However, in the case of providing the control layer having such a metalpart between the light emitting element and the light detecting element,the light emitting element and the light detecting element may not beformed in a lump by crystal growth on the same substrate. Consequently,usually, the light emitting element and the light detecting element areformed on different substrates. The control layer is provided on thesurface of at least one of the light emitting element and the lightdetecting element. The light emitting element and the light detectingelement are adhered to each other with the control layer in between,thereby integrally forming the light emitting element and the lightdetecting element.

Generally, at the time of adhering the light emitting element and thelight detecting element to each other with the control layer in between,in a state where the light emitting element and the light detectingelement are disposed so as to face each other and the temperature is setto be high, pressure is applied in the stack direction. However, whenpressure is increased to improve adhesion between the light emittingelement and the light detecting element, there is the possibility that adefect such as a crack occurs in the light emitting element and thelight detecting element. When the pressure is decreased to preventoccurrence of a defect such as a crack in the light emitting element andthe light detecting element, there is the possibility that adhesionbetween the light emitting element and the light detecting elementdeteriorates.

As described above, the conventional method has a disadvantage such thatthe yield easily deteriorates in the process of adhering the lightemitting element and the light detecting element. Such a disadvantagealways occurs at the time of adhering the elements to each other.

It is therefore desirable to provide a semiconductor device and a methodof manufacturing the same realizing suppression of occurrence of adefect such as a crack at the time of adhering the elements to eachother.

According to an embodiment of the present invention, there is provided afirst semiconductor device including a first element and a secondelement adhered to each other. At least one of the first and secondelements has a pressure relaxation layer on the side facing the other ofthe first and second elements, and the pressure relaxation layerincludes a semiconductor part having a projection/recess part includinga projection projected toward the other element, and a resin part filledin a recess in the projection/recess part.

In the first semiconductor device of the embodiment of the presentinvention, at least one of the first and second elements adhered to eachother is provided with the pressure relaxation layer including asemiconductor part having a projection/recess part including aprojection projected toward the other element, and a resin part filledin a recess in the projection/recess part. With the configuration, in amanufacturing process, at the time of adhering the elements whileapplying pressure in a state where the projecting direction of theprojection in the projection/recess part is set toward the otherelement, the pressure applied to the first and second elements isrelaxed by the elasticity of the resin part.

According to an embodiment of the present invention, there is provided asecond semiconductor device including a first element and a secondelement adhered to each other. At least one of the first and secondelements has a semiconductor part and a resin part.

In the second semiconductor device of the embodiment of the presentinvention, at least one of the first and second elements adhered to eachother is provided with a semiconductor part and a resin part. With theconfiguration, for example, at the time of adhering the first and secondelements while applying pressure in a state where the first and secondelements are disposed so as to face each other, the pressure applied tothe first and second elements is relaxed by the elasticity of the resinpart.

According to an embodiment of the present invention, there is provided amethod of manufacturing the first semiconductor device including thesteps of preparing a first element and a second element at least one ofwhich has, on its one of faces, a pressure relaxation layer including asemiconductor part having a projection/recess part and a resin partfilled in a recess in the projection/recess part, and adhering the firstand second elements to each other by applying pressure in a state whereprojecting direction of the projection in the projection/recess part isset toward the other element.

In the method of manufacturing the first semiconductor device of theembodiment of the present invention, at least one of the first andsecond elements is provided with, on the adhesion side, the pressurerelaxation layer including a semiconductor part having aprojection/recess part and a resin part filled in a recess in theprojection/recess part. Therefore, the pressure applied to the first andsecond elements is relaxed by the elasticity of the resin part.

According to an embodiment of the present invention, there is provided amethod of manufacturing the second semiconductor device including a stepof adhering first and second elements at least one of which has asemiconductor part and a resin part to each other while applyingpressure in a state where the first and second elements are disposed soas to face each other.

In the method of manufacturing the second semiconductor device of theembodiment of the present invention, at least one of the first andsecond elements is provided with the semiconductor part and the resinpart, so that the pressure applied to the first and second elements isrelaxed by the elasticity of the resin part.

In the first and second semiconductor devices of the embodiment of thepresent invention, at the time of adhering the first and second elementsto each other in the manufacturing process, the pressure applied to thefirst and second elements may be relaxed by the elasticity of the resinpart. Also in the case where large pressure is applied to the first andsecond elements, an excessive amount of the pressure is lessened by theresin part. Therefore, occurrence of a defect such as a crack may bereduced at the time of adhering the elements to each other.

By the method of manufacturing the first and second semiconductordevices of the embodiment of the present invention, the pressure appliedto the first and second elements may be relaxed by the elasticity of theresin part. Also in the case where large pressure is applied to thefirst and second elements, an excessive amount of the pressure islessened by the resin part. Therefore, occurrence of a defect such as acrack may be reduced at the time of adhering the elements to each other.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional configuration diagram of a semiconductor lightemitting device as a first embodiment of the invention.

FIG. 2 is a cross section showing an example of a sectionalconfiguration taken along line A-A of FIG. 1.

FIG. 3 is a cross section showing another example of the sectionalconfiguration taken along line A-A of FIG. 1.

FIGS. 4A and 4B are cross sections illustrating a manufacturing processof the semiconductor light emitting device.

FIG. 5 is a cross section illustrating a process subsequent to FIG. 4B.

FIG. 6 is a cross section illustrating a process subsequent to FIG. 5.

FIGS. 7A and 7B are cross sections illustrating a process subsequent toFIG. 6.

FIG. 8 is a cross section illustrating a process subsequent to FIG. 7B.

FIG. 9 is a cross section illustrating a process subsequent to FIG. 8.

FIGS. 10A and 10B are cross sections illustrating a process subsequentto FIG. 9.

FIGS. 11A and 11B are cross sections illustrating a process subsequentto FIG. 10B.

FIG. 12 is a cross section illustrating the operation of thesemiconductor light emitting device.

FIG. 13 is a sectional configuration diagram of a semiconductor lightemitting device as a modification.

FIG. 14 is a sectional configuration diagram of a semiconductor lightemitting device as a second embodiment of the present invention.

FIG. 15 is a sectional configuration diagram of a semiconductor lightemitting device as a modification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described hereinbelow withreference to the drawings.

First Embodiment

FIG. 1 shows a sectional configuration of a semiconductor light emittingdevice as a first embodiment of the present invention. FIG. 2 shows asectional configuration taken along line A-A of FIG. 1. FIG. 1corresponds to a sectional configuration taken along line B-B of FIG. 2or 3. FIGS. 1 to 3 are schematic diagrams, and dimensions and shapes aredifferent from actual ones. The semiconductor light emitting device isconstructed by disposing, on a light detecting element 1, a controllayer 2 and a vertical cavity surface emitting laser (VCSEL) 3 in order.The light detecting element 1, the control layer 2, and the VCSEL 3 areintegrally formed.

In the semiconductor light emitting device, light of the VCSEL 3 isemitted from an aperture 39A (which will be described later) to theoutside and is slightly output to the light detecting element 1 via thecontrol layer 2. Specifically, in the semiconductor light emittingdevice, the control layer 2 and the light detecting element 1 arestacked in this order on the VCSEL 3 on the side opposite to the sidewhere the light of the VCSEL 3 is emitted to the outside. An electricsignal (photocurrent) according to the output level of light leaked tothe light detecting element 1 side is output from the light detectingelement 1.

VCSEL 3

The VCSEL 3 has a stack stntcture in which, for example, a p-typecontact layer 31, a p-type DBR layer 32, a current confinement layer 33,a p-type cladding layer 34, an active layer 35, an n-type cladding layer36, an n-type DBR layer 37, and an n-type contact layer 38 are stackedin order on the control layer 2. The stack structure has, for example, amesa shape including steps in the p-type DBR layer 32.

The p-type contact layer 31 is made of, for example, p-typeAl_(x1)Ga_(1-x1)As (0≤x1≤1). Examples of p-type impurity are zinc (Zn),magnesium (Mg), beryllium (Be), and carbon (C).

The p-type DBR layer 32 is constructed by alternately stacking alow-refractive-index layer (not shown) and a high-refractive-index layer(not shown). The low-refractive-index layer is made of, for example,p-type Al_(x2)Ga_(1-x2)As (0<x2≤1) having a thickness of λo/4n₁ (n₁denotes refractive index), and the high-refractive-index layer is madeof, for example, p-type Al_(x3)Ga_(1-x3)As (0≤x3<x2) having a thicknessof λo/4n₂ (n₂ denotes refractive index).

The current confinement layer 33 has a current confinement area 33B inits outer edge area and a current injection area 33A in its center area.The current injection area 33A is made of, for example, p-typeAl_(x4)Ga_(1-x4)As (0<x4≤1). The current confinement area 33B is madeof, for example, a material containing Al₂O₃ (aluminum oxide) and, aswill be described later, is obtained by oxidizing Al of high densityincluded in a current confinement layer 33D from the side face.Therefore, the current confinement layer 33 has the function ofconfining current.

The p-type cladding layer 34 is made of, for example, p-typeAl_(x5)Ga_(1-x5)As (0≤x5≤1). The active layer 35 is made of, forexample, undoped Al_(x6)Ga_(1-x6)As (0≤x6≤1). In the active layer 35, anarea facing the current injection area 33A is a light emission area 35A.The n-type cladding layer 36 is made of, for example, n-typeAl_(x7)Ga_(1-x7)As (0≤x7≤1).

The n-type DBR layer 37 is formed by alternately stacking alow-refractive-index layer (not shown) and a high-refractive-index layer(not shown). The low-refractive-index layer is made of, for example,n-type Al_(x8)Ga_(1-x8)As (0<x8≤1) having a thickness of λo/4n₃ (n₃denotes refractive index), and the high-refractive-index layer is madeof, for example, n-type Al_(x9)Ga_(1-x9)As (0≤x9<x8) having a thicknessof λo/4n₄ (n₄ denotes refractive index).

The n-type contact layer 38 is made of, for example, n-typeAl_(x10)Ga_(1-x10)As (0≤x10≤1). The n-type contact layer 38 has, forexample, an aperture corresponding to the light emission area 35A andhas a donut shape.

The VCSEL 3 also includes an n-side electrode 39 on the n-type contactlayer 38. The n-side electrode 39 has a structure obtained by stacking,for example, an alloy of gold (Au) and germanium (Ge), nickel (Ni), andgold (Au) in order from the n-type contact layer 38 side, and iselectrically connected to the n-type contact layer 38. The n-sideelectrode 39 has, for example, the aperture 39A in correspondence withthe light emission area 35A and has a donut shape.

Control Layer 2

The control layer 2 has a light transmitting part 21 and a metal part 22in the same plane. The light transmitting part 21 is provided at leastin a part of an area facing the light emission area 35A in the VCSEL 3.The metal part 22 is provided around the light transmitting part 21. Inthe relation with light emitted from the VCSEL 3, it is said that themetal part 22 has an aperture at least in a part of the area facing thelight emission area 35A. FIG. 1 shows the case where the lighttransmitting part 21 is provided in the whole area facing the lightemission area 35A.

The light transmitting part 21 is made of a material capable oftransmitting light emitted from the light emission area 35A, forexample, an insulting material such as SiN, SiO₂ or air. The lighttransmitting part 21 transmits light released to the light detectingelement 1 side in the light emitted from the light emission area 35A. Onthe other hand, the metal part 22 is made of a metal having highreflectance, for example, gold (Au) or the like. The metal part 22reflects the light emitted to an area other than the light transmittingpart 21 in the light emitted to the light detecting element 1 sidetoward the VCSEL 3 side, thereby interrupting entrance to the lightdetecting element 1. That is, the control layer 2 has not only thefunction of joining the light detecting element 1 and the VCSEL 3 toeach other but also the function of regulating the incidence area oflight to the light detecting element 1. The metal part 22 iselectrically connected to the p-type contact layer 31 in the VCSEL 3 andalso functions as the p-side electrode of the VCSEL 3.

Preferably, the control layer 2 is formed, for example, according to amanufacturing method which will be described later. At the time ofoverlapping the light detecting element 1 and the VCSEL 3, a controllayer 2A having a light transmitting part 21A and a metal part 22A andformed on the surface of the light detecting element 1 and a controllayer 2B having a light transmitting part 21B and a metal part 22B andformed on the surface of the VCSEL 3 are joined to each other.

In this case, by joining the light transmitting parts 21A and 21B toeach other, the light transmitting part 21 is formed. By joining themetal parts 22A and 22B, the metal part 22 is formed. The control layer2 may be formed in advance on the surface of either the light detectingelement 1 or the VCSEL 3 at the time of overlapping the light detectingelement 1 and the VCSEL 3.

Light Detecting Element 1

The light detecting element 1 has, on a substrate 10, a light absorptionlayer 11, a p-type semiconductor part 12, and a resin part 13 in orderfrom the substrate 10 side and has, on the back side of the substrate10, an n-side electrode 14. The p-type semiconductor part 12 and theresin part 13 are formed in the same plane.

The substrate 10 is made of, for example, n-type GaAs. The lightabsorption layer 11 is made of, for example, Al_(x11)Ga_(1-x11)As(0≤x11≤1) and is provided at least in an area facing the lighttransmitting part 21. With the configuration, the light absorption layer11 absorbs part of light output from the light emission area 35A andconverts the absorbed light to an electric signal. The electric signalis input as a light output monitor signal to a light output computingcircuit (not shown) connected to the light detecting element 1, and usedfor measuring the output level of light passed through the control layer2 in the light output computing circuit.

The p-type contact part 12 is made of, for example, p-typeAl_(x12)Ga_(1-x12)As (0≤x12≤1). High-concentration p-type impurity maybe doped only in an upper part of the p-type semiconductor part 12. Thep-type semiconductor part 12 has, in a stack plane, a projection/recesspart 12A including one or more projections 12A-1 and one or morerecesses 12A-2. The projection 12A-1 projects toward the VCSEL 3 (on theside of the VCSEL 3, of the p-type semiconductor part 12).

Preferably, the projection/recess part 12A is provided on the side ofthe surface facing the VCSEL 3, and the height of the projection 12A-1(the depth of the recess 12A-2) is 1 μm or greater. In this case,elasticity of the resin part 13 may be used more effectively in anadhering process which will be described later. Preferably, theprojection 12A-1 has conductivity and is electrically connected to themetal part 22. In this case, the metal part 22 can be used as a p-sideelectrode of the light detecting element 1.

The recess 12A-2 is filled with the resin part 13. The resin part 13 ismade of a resin material having a property of transmitting light emittedfrom the VCSEL 3 such as polyimide. Generally, resin material haselasticity higher than that of semiconductor material and thermalconductivity lower than that of semiconductor material. Preferably, therecess 12A-2 is provided at least in an area facing the lighttransmitting part 21. In this case, the light passed through the lighttransmitting part 21 in the light emitted from the VCSEL 3 is led to thelight absorption layer 11 while suppressing attenuation of the light asmuch as possible.

The recess 12A-2 may be a dent or groove formed in the surface on thecontrol layer 2 side of the p-type semiconductor part 12 or a holepenetrating the p-type semiconductor part 12 as shown in FIG. 1. In thecase where the recess 12A-2 is a hole, as shown in FIG. 1, the lightabsorption layer 11 is exposed from the bottom of the recess 12A-2.

The n-side electrode 14 has a structure in which, for example, an AuGealloy, Ni, and Au are stacked in order from the substrate 10 side, andis electrically connected to the substrate 10.

The semiconductor light emitting device having such a configuration ismanufactured as follows. FIGS. 4A and 4B to FIGS. 11A and 11B show themanufacturing method in the process order.

First, on the substrate 10, the light absorption layer 11 and the p-typesemiconductor part 12 are stacked in this order (FIG. 4A). Subsequently,a photoresist (not shown) is formed in an area including the area facingan area where the metal part 22 is to be formed. Using the photoresistas a mask, the p-type semiconductor part 12 is selectively removed by,for example, dry etching to expose a part of the light absorption layer11 (FIG. 4B). As a result, the projection/recess part 12A including theprojections 12A-1 and the recess 12A-2 is formed in the p-typesemiconductor part 12. After that, the mask is removed.

The recess 12A-2 is filled with a resin such as polyimide to therebyforming the resin part 13 (FIG. 5). At this time, the height of theresin part 13 is set to be equal to or higher than that of theprojection 12A-1.

Next, on a substrate 40 made of, for example, n-type GaAs, the n-typecontact layer 38, the n-type DBR layer 37, the n-type cladding layer 36,the active layer 35, the p-type cladding layer 34, the currentconfinement layer 33D, the p-type DBR layer 32, and the p-type contactlayer 31 are stacked in this order (FIG. 6).

An insulating material such as SiO₂ is deposited on the p-typesemiconductor part 12, the resin part 13, and the p-type contact layer31, and a photoresist (not shown) is formed in an area corresponding tothe light emission area 35A in the surface of the deposited insulatingmaterial. Subsequently, the photoresist is used as a mask and theinsulating material is selectively removed by, for example, wet etchingusing a hydrofluoric acid etchant, thereby forming the lighttransmitting parts 21A and 21B. A metal such as gold (Au) is depositedby the vacuum evaporation method and the photoresist is removed, therebyforming the metal parts 22A and 22B. In such a manner, the controllayers 2A and 2B are formed (FIGS. 7A and 7B).

The control layers 2A and 2B are set so as to face each other. In astate where the projection direction of the projections 12A-1 is settoward the control layer 2B and the temperature is set to be high, thecontrol layers 2A and 2B are adhered to each other while applying apressure F from the substrates 10 and 40 sides (FIG. 8). As a result,the control layer 2 is formed, and the substrates 10 and 40 are adheredto each other with the control layer 2 in between. After that, thesubstrate 40 is removed by, for example, wet etching (FIG. 9).

Next, a mask (not shown) is formed in a predetermined area in thesurface of the n-type contact layer 38. The n-type contact layer 38, then-type DBR layer 37, the n-type cladding layer 36, the active layer 35,the p-type cladding layer 34, the current confinement layer 33D, and apart of the p-type DBR layer 32 are selectively removed by, for example,dry etching, thereby forming a mesa shape. After that, the mask isremoved (FIG. 10A). At this time, a part of the p-type DBR layer 32 isexposed.

An oxidizing process is performed at high temperature in the vaporatmosphere to selectively oxidize the current confinement layer 33D fromthe side face of the mesa. By the operation, the outer peripheral areaof the current confinement layer 33D becomes an insulating layer(aluminum oxide). As a result, the current confinement area 33B isformed in the outer peripheral area, and the center area becomes thecurrent injection area 33A. In such a manner, the current confinementlayer 33 is formed (FIG. 10B).

In a manner similar to the above, the exposed portion in the p-type DBRlayer 32 and the p-type contact layer 31 are selectively removed (FIG.11A), thereby forming a mesa shape having a step in some midpoint of thep-type DBR layer 32 and exposing a part of the metal part 22.Subsequently, a mask (not shown) having an aperture in a center portionof the top face of the mesa is formed. For example, by wet etching, anaperture is formed in the n-type contact layer 38. After that, the maskis removed (FIG. 11B).

Next, for example, by evaporation, the n-side electrode 39 having theaperture 39A is formed on the surface of the n-type contact layer 38and, further, the n-side electrode 14 is formed on the back side of thesubstrate 10 (FIG. 1). In such a manner, the semiconductor lightemitting device of the embodiment is manufactured.

In the semiconductor light emitting device of the embodiment, when apredetermined voltage is applied across the metal part 22 as a p-sideelectrode and the n-side electrode 39, the current narrowed by thecurrent confinement layer 33 is injected to the light emission area 35Aas a gain area in the active layer 35. As a result, light is generatedby recombination of electrons and positive holes. The light includes notonly light generated by stimulated emission but also light generated byspontaneous emission. As a result of repetition of stimulated emissionin the device, a laser oscillation occurs at a predetermined wavelengthXo. Light L1 including the wavelength λo is output to the outside, andlight L2 including the wavelength λo is output to the light detectingelement 1 side (FIG. 12).

Since the light absorption layer 11 in the light detecting element 1 isdisposed in correspondence with the light emission area 35A, the lightL2 passes through the light transmitting part 21 and the resin part 13and is incident on the light absorption layer 11. A part of the light L2incident on the light absorption layer 11 is absorbed by the lightabsorption layer 11 and converted to an electric signal (photocurrent)according to the output level of the absorbed light. The electric signalhas intensity according to the output level of light output from theVCSEL 3 to the outside. The electric signal is output to a light outputcomputing circuit (not shown) via a wire (not shown) electricallyconnected to the metal part 22 as the p-side electrode and the n-sideelectrode 14 and then received as a light output monitor signal in thelight output computing circuit. In such a manner, the output level ofthe light output from the VCSEL 3 to the outside is measured.

Most of the spontaneous emission light (light L2) output to the lightdetecting element 1 side passes through the light transmitting part 21and the resin part 13 and enter the light detecting element 1. On theother hand, most of the spontaneous emission light (light L3) output tothe light detecting element 1 side is reflected by the metal part 22toward the VCSEL 3 side, and incidence to the light detecting element 1is interrupted for the following reason. The stimulated emission lighthas directivity and is hardly released to the metal part 22 side.Meanwhile, the spontaneous emission light does not have directivity andmost of it is released to the metal part 22 side. Consequently, theamount of the spontaneous emission light passing through the lighttransmitting part 21 is made much smaller than that of the stimulatedemission light passing through the light transmitting part 21. Since thereflectance of the metal part 22 is usually extremely high, the amountof the spontaneous emission light passing through the metal part 22 isignorable as compared with the amount of the spontaneous emission lightpassing through the light transmitting part 21.

Therefore, in the semiconductor light emitting device of the embodiment,the control layer 2 having the light transmitting part 21 and the metalpart 22 is provided between the VCSEL 3 and the light detecting element1, so that entry of the spontaneous emission light released to thecontrol layer 2 side to the light detecting element 1 is substantiallyinterrupted. As a result, the detection level of the spontaneousemission light by the light detecting element 1 is lowered, so thatlight detection precision is further improved.

In the embodiment, the resin part 13 is provided near the control layer2 adhering the light detecting element 1 and the VCSEL 3. The resin part13 is made of a resin material having elasticity higher than that of asemiconductor material. Consequently, in the process of adhering thelight detecting element 1 and the VCSEL 3, the pressure F applied to theelements is relaxed by the elasticity of the resin part 13. Even in thecase where the pressure F is high, an excessive amount of the pressureis lessened by the resin part 13. Therefore, occurrence of a defect suchas a crack is reduced at the time of adhering the light detectingelement 1 and the VCSEL 3.

In the embodiment, the resin part 13 is made of a resin material havingthermal conductivity lower than that of the semiconductor material. Byproperly adjusting the position and the shape of the recess 12A-2, thearea ratio between the projection 12A-1 and the recess 12A-2, the kindof the resin material, and the like, for example, in a process ofmounting the semiconductor light emitting device on a sub-mount, a heatsink, a can, or the like via a solder, the resin part 13 suppressesrapid conduction of heat from the light detecting element 1 side to theVCSEL 3 side. It eliminates the possibility that the VCSEL 3 is heatedexcessively. Thus, heat resistance of the semiconductor light emittingdevice is increased.

Since the p-type semiconductor part 12 (the projection 12A-1) containsthe p-type impurity and the substrate 10 contains the n-type impurity,they have conductivity. Further, the p-type semiconductor part 12 (theprojection 12A-1) is electrically connected to the metal part 22, andthe substrate 10 is electrically connected to the n-side electrode. Withthe configuration, an electric signal converted by the light absorptionlayer 11 may be taken from the metal part 22 and the n-side electrode14. That is, the metal part 22 has not only the function of suppressingentry of the spontaneous emission light to the light detecting element 1but also the function of the p-side electrode of the light detectingelement 1. Therefore, it is unnecessary to provide a p-side electrodefor the light detecting element 1. The metal part 22 is electricallyconnected also to the p-type contact layer 31 of the VCSEL 3. That is,since the metal part 22 also functions as the p-side electrode of theVCSEL 3, it is unnecessary to provide a p-side electrode for the VCSEL3.

Since the control layer 2 is formed by using a technique of extremelyhigh process precision such as photolithography, as compared with thecase of forming an oxidation layer that disturbs transmission of thespontaneous emission light by oxidizing a part of the semiconductorlayer by using an oxidation process whose controllability is not easylike Japanese Patent No. 2,877,785, the shape, size, and the like isobtainable with higher precision. Therefore, variations in theproperties of semiconductor light emitting devices may be reducedlargely.

It is also unnecessary to use a process causing volume shrinkage such asoxidation of a semiconductor layer like in Japanese Patent No. 2,877,785or the like in order to eliminate the spontaneous emission light. Thereis consequently no possibility that peeling caused by volume shrinkageoccurs in the control layer 2. Thus, the yield and reliability is muchhigher than that in the case of forming a layer for eliminating thespontaneous emission light by using the process accompanying volumeshrinkage such as oxidation of a semiconductor layer.

Since the metal parts 22A and 22B are joined to each other, adhesionbetween the light detecting element 1 and the VCSEL 3 may be increased.Since the joined parts do not peel from each other, it is not fearedthat the yield and reliability deteriorates due to the joining.

Since the light detecting element 1 and the VCSEL 3 are crystal-grown ondifferent substrates, as compared with the case where they are formed onthe same substrate, crystal growth may be performed at higher quality.As a result, the device properties and reliability are further improved.

Modification of First Embodiment

In the foregoing embodiment, the p-type semiconductor part 12 and theresin part 13 are provided on the light detecting element 1 side.Alternately, they may be provided on the VCSEL 3 side, as shown in FIG.13. Also in the case of providing the resin part 13 on the VCSEL 3 side,effects similar to those of the foregoing embodiment are produced. Inthis case, it is preferable to provide the p-type contact layer 15between the contact layer 2 and the light absorption layer 11.

Second Embodiment

FIG. 14 shows the structure of a semiconductor light emitting device asa second embodiment of the present invention. FIG. 14 is a schematicdiagram and dimensions and shapes in FIG. 14 are different from actualones. In the following description, when the same reference numeral asthat in the foregoing embodiment is used, it means that the componenthas the configuration and function similar to those of the componenthaving the same reference numeral.

The semiconductor light emitting device is formed by disposing thecontrol layer 2 and a light detecting element 5 in order on a VCSEL 4and integrally forming the VCSEL 4, the control layer 2, and the lightdetecting element 5. In the semiconductor light emitting device, lightemitted from the VCSEL 4 goes out via the control layer 2 and the lightdetecting element 5 from an aperture 17A (which will be described later)to the outside. Further, an electric signal according to the outputlevel of light entering the light detecting element 5 is output from thelight detecting element 5.

Specifically, in the semiconductor light emitting device, the controllayer 2 and the light detecting element 5 are disposed in this order onthe side where light emitted from the VCSEL 4 mainly goes out to theoutside. The positions of the control layer 2 and the light detectingelement 5 relative to the VCSEL 4 are mainly different from those of theforegoing embodiment. In the following, the different point will bemainly described in detail, and the description of the configurations,operations, and effects similar to those of the foregoing embodimentwill not be repeated.

VCSEL 4

The VCSEL 4 has a stack structure in which the n-type DBR layer 37, then-type cladding layer 36, the active layer 35, the p-type cladding layer34, the current confinement layer 33, the p-type DBR layer 32, and thep-type contact layer 31 are stacked in order on the surface of asubstrate 41. An n-side electrode 42 is formed on the back side of thesubstrate 41. The substrate 41 is made of, for example, n-type GaAs. Then-side electrode 42 has a structure in which, for example, an AuGealloy, Ni, and Au are stacked in order from the substrate 40 side and iselectrically connected to the substrate 41.

Light Detecting Element 5

The light detecting element 5 has, on the control layer 2, the p-typesemiconductor part 12 and the resin part 13 formed in the same plane,the light absorption layer 11, the n-type contact layer 16, and then-side electrode 17 in order from the control layer 2 side. The n-typecontact layer 16 is made of, for example, n-type Al_(x12)Ga_(1-x12)As(0≤x12≤1). The n-type contact layer 16 has, for example, an aperture incorrespondence with the light emission area 35A and has a donut shape.The n-side electrode 17 has a stack structure in which an AuGe alloy,Ni, and Au are stacked in order from the control layer 2 side, and iselectrically connected to the substrate 41. The n-side electrode 17 has,for example, the aperture 17A in correspondence with the light emissionarea 35A and has a donut shape.

In the semiconductor light emitting device of the embodiment, like theforegoing embodiment, the control layer 2 having the light transmittingpart 21 and the metal part 22 is provided between the VCSEL 4 and thelight detecting element 1, so that entry of the spontaneous emissionlight released to the control layer 2 side to the light detectingelement 1 is substantially interrupted. As a result, the detection levelof the spontaneous emission light by the light detecting element 1 maybe lowered, so that light detection precision may be further improved.

In the embodiment, like the foregoing embodiment, the resin part 13 isprovided near the control layer 2 adhering the light detecting element 1and the VCSEL 4. Consequently, even in the case where the pressure F ishigh, an excessive amount of the pressure is lessened by the resin part13. Therefore, occurrence of a defect such as a crack may be reduced atthe time of adhering the light detecting element 1 and the VCSEL 4.

Modification of Second Embodiment

Although the p-side semiconductor part 12 and the resin part 13 areprovided on the light detecting element 5 side in the foregoingembodiment, as shown in FIG. 15, they may be provided on the VCSEL 4. Asdescribed above, also in the case of providing the resin part 13 on theVCSEL 4 side, effects similar to those of the embodiment are produced.In this case, it is preferable to provide a p-type contact layer 18between the control layer 2 and the light absorption layer 11.

Although the present invention has been described by the embodiments,the invention is not limited to the embodiments but can be variouslymodified.

For example, the case of using a GaAs-based compound semiconductor asthe semiconductor material has been described in the foregoingembodiments, other materials such as a GaInP-based (red-based) material,an AlGaAs-based (infra-red-based) material, a GaN-based(blue-green-based) material, or the like may be also used.

In the foregoing embodiments, the measures of applying the presentinvention to the case of integrally forming the surface-emittingsemiconductor laser and the light detecting element via the controllayer 2 have been described. The invention is also applicable to thecase of using another light emitting device such as a light emittingdiode in place of the surface-emitting semiconductor laser. Theinvention is also applicable to the case of using a conductive substratecapable of passing current in the thickness direction in place of alight detecting element.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alternations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A semiconductor device comprising: a laserconfigured to radiate a light emission, part of the light emission beingtransmissible through a light transmitting part of a control layer and aresin part of a projection/recess part; a group III-V compound lightabsorption layer configured to convert said part of the light emissioninto an electric signal, said control layer and said projection/recesspart being between said laser and said light absorption layer.
 2. Thesemiconductor device according to claim 1, wherein said lighttransmitting part is an insulating material.
 3. The semiconductor deviceaccording to claim 1, wherein said light absorption layer is made ofAl_(x11)Ga_(1-x11)As, with 0≤x11≤1.
 4. The semiconductor deviceaccording to claim 1, wherein said light absorption layer is a p-typelayer.
 5. The semiconductor device according to claim 1, wherein saidresin part physically contacts said light transmitting part.
 6. Thesemiconductor device according to claim 1, wherein said control layer isbetween said laser and said projection/recess part.
 7. The semiconductordevice according to claim 6, wherein said projection/recess part isbetween said control layer and said light absorption layer.
 8. Thesemiconductor device according to claim 1, wherein said lighttransmitting part is between said resin part and said laser.
 9. Thesemiconductor device according to claim 8, wherein said laser physicallycontacts said light transmitting part.
 10. The semiconductor deviceaccording to claim 1, wherein said projection/recess part is betweensaid laser and said control layer.
 11. The semiconductor deviceaccording to claim 10, wherein said control layer is between saidprojection/recess part and said light absorption layer.
 12. Thesemiconductor device according to claim 1, wherein said resin part isbetween said light transmitting part and said laser.
 13. Thesemiconductor device according to claim 12, wherein said laserphysically contacts said resin part.
 14. The semiconductor deviceaccording to claim 1, wherein a metal part of the control layer isconfigured to reflect said light emission.
 15. The semiconductor deviceaccording to claim 14, wherein said metal part is around said lighttransmitting part.
 16. The semiconductor device according to claim 1,wherein said resin part is a resin material.
 17. The semiconductordevice according to claim 16, wherein said resin material has elasticityhigher than that of semiconductor material, thermal conductivity ofresin material being lower than that of said semiconductor material. 18.The semiconductor device according to claim 1, wherein a hole is througha semiconductor part of the projection/recess part, said resin partbeing in said hole.
 19. The semiconductor device according to claim 18,wherein said semiconductor part is a p-type layer.
 20. The semiconductordevice according to claim 18, wherein said semiconductor part is made ofAl_(x12)Ga_(1-x12)As with 0≤x12≤1.
 21. The semiconductor deviceaccording to claim 1, wherein said laser is a vertical cavity surfaceemitting laser, a first DBR layer of the vertical cavity surfaceemitting laser being between an active layer of the vertical cavitysurface emitting laser and said light absorption layer.
 22. Thesemiconductor device according to claim 21, wherein an active layer isbetween said first DBR layer and a second DBR layer.
 23. A semiconductordevice comprising: a light emitting device configured to radiate a lightemission; a control layer that includes a light transmitting member; aprojection/recess member that includes a resin; and a group III-Vcompound light absorption layer configured to convert a part of thelight emission into an electric signal, wherein the part of the lightemission is transmissible through the light transmitting member and theresin, and wherein the control layer and the projection/recess memberare between the light emitting device and the group III-V compoundabsorption layer.
 24. The semiconductor device according to claim 23,wherein the projection/recess member is between the light emittingdevice and the control layer.